Novel phosphorodithioates and methods for preparing the same



States Patent Gfifioe 3,019,159 Patented Jan. 30, 1962 of Maine NDrawing. Filed May 11, 1960, Ser. No. 28,236

12 Claims.

The present invention relates to novel phosphorodithioates reprented bythe general formula:

Rczc-s-l wrtm in which R is a lower alkyl or aryl radical and R is loweralkyl and method for the preparation thereof.

Phosphorothioate compounds of the present invention, which have thegeneral grouping:

find utility as pesticides and, particularly, as insecticides.

They are prepared by admixing in an inert organic solvent and in anydesired order, 0,0,0',O'-tetraalkyl dithiophosphonothioate having thegeneral structure:

wherein R is a lower alkyl radical, and approximately equimolarquantities of an alkali metal salt of a primary acetylene, such asmethyl acetylene and phenyl acetylene, conforming to the structure:

(2) RCECM wherein R is a lower alkyl or aryl radical and M is an alklimetal such as sodium, potassium and lithium. Reaction may be carried outand occurs at temperatures ranging from about 0 C. to about 50 C., andpreferably from about 30 C. to 40 C.

Known dithiophosphonothioates which can be employed herein are:

0,0,0,0-tetramethyl dithiophosphonothioate 0,0,0,O'-tetraethyldithiophosphonothioate 0,0,0',O'-tetrabutyl dithiophosphonothioate0,0,0',O-tetrapheny1 dithiophosphonothioate 0,0,0',O'-tetranaphthyldithiophosphonothioate Suitable inert solvents for the aforementionedreaction include: hexane, cyclohexane, dioxane, ether, xylene, tolueneand the like.

The compounds of the present invention are highly active insecticidesand may be used as sprays in organic solvents, as emulsions in water orother non-solvents, or on solid carriers, such as talc, clays,diatomaceous earths and the like. Such amounts of inert carrier may beused as are customarily employed in the art. However, the activepesticidal compound is present in amounts ranging from about 0.1% toabout 5%, based on the weight of the inert carrier.

In order to facilitate a further understanding of the invention, thefollowing examples are given primarily for purposes of illustrating morespecific details thereof. It is to be understood, however, that thescope of the invention is not to be deemed limited thereby, except asUnless otherwise noted, the parts EXAMPLE 1 Preparation of 0,0-diethyl,S-phenylethynyl phosphorodithioate To a solution of 3.8 parts ofphenylacetylene (0.03 mol) in 15 parts of volume of anhydrous ethylether were slowly added 10 parts by Volume of a 3 N butyl lithium inhexane while stirring in a suitable reaction vessel. The mixture iscooled in an ice bath during reaction. Suflicient ether is added todissolve any precipiated lithium salt. Next, the solution is addedslowly to 10 parts of 0,0,0,O-tetraethyl dithiophosphonothioate (0.03mol). After stirring for an additional hour, the ether solution iswashed with water and dried over magnesium sulfate. Evaporation of thesolvent yields 7.3 parts of a light brown liquid. The latter isdistilled at 12-18 mm, Hg pressure to obtain 4.9 parts of 0,0-diethy1,S-phenylethynyl phosphorodithioate having a refractive index of15903-15918 at 25 C. Analysis (in percent) of the compound showed thefollowing.

Calculated: P, 10.82; S, 22.38. Found: P, 10.33; S, 22.70.

defined in the claims. are by weight.

EXAMPLE 2 Preparation of 0,0-dz'ethyl, S-methylerhynylphosphorodithioate Into a suitable reaction vessel is passed methylacetylene gas into a solution of 25 parts of 3.03 N butyl lithium inhexane (0.076 mol) and 150 parts of ether, The mixture is rapidlystirred and cooled on an ice bath. When formation of lithium methylacetylide is complete, 25 parts of 0,0,0',O'-tetraethyldithiophosphonothioate (0.06 mol) in 50 parts of ether are added. Themixture is stirred for one-half hour, then refluxed for 15 minutes,cooled and washed with water. The ether solution is then dried overmagnesium sulfate. Evaporation of the salt leaves 13.7 parts of a lightbrown liquid. The latter is distilled at 0.8 mm. Hg pressure yielding10.8 parts of '0,0-diethyl, S-methylethynyl phosphorodithioate having aboiling point of -100 C. and an index of refraction at and analyzes afollows,

Calculated for PS O C H C, 37.50; H, 5.85; P, 13.69; S, 28.55. Found: C,37.59; H, 6.09; P, 13.75; S, 28.85.

EXAMPLE 3 Preparation of 0,0-dimethyl, S-phenylerhynylprosphorodithioate Repeating Example 1 except that 0,0,0',O'-tetramethyldithiophosphonothioate is employed in lieu of the correspondingtetraethyl di-thiophosphonothioate derivative, a black liquid, in 95%yield, having a refractive index n =L6l04 is obtained.

Other typical phosphorodithioates of the present invention, which areprepared according to the practice of Example 1, are:

0,0-diethyl-S-naphthylethynyl phosphorothioate0,0-diethyl-S-isopropylethynyl phosphorothioate0,0-dimethyl-S-n-propylethynyl phosphorothioate0,0-diethyl-S-n-butylethynyl phosphorothioate0,0-diethyl-S-tertiarybutylethynyl phosphorothioate As above stated, thecompounds of the invention are highly active insecticides. Todemonstrate the marked degree of insecticidal activity, each of theproducts of the above examples are dissolved in a solvent thereforcomprising 65% acetone and 35% water at a concentration of 0.01% basedon the Weight of the compound. The

9 .1 solution is sprayed on Nasturtium aphids and the results of thetests are tabularized below: TABLE I Compound Percent Kill 0,0-Diethyl,S'Ihenylethynyl Phosphorodithioate. 49 8,8-Diethyl, S-MethylethynylPhosphorodithioate g a -Dimethyl, SPhenylethynyl Phosphorodithioatenczc-sawnm wherein R is a radical selected from the group consisting oflower alkyl, phenyl and naphthyl and R is a lower alkyl radical, whichcompn'ses: reacting an alkali metal acetylide having the structure:

RCECM where R is a radical selected from the group consisting of loweralkyl and aryl and M is an alkali metal, with a dithiophosphonothioateof the structure:

where R is a lower alkyl radical.

6. A process according to claim 5 in which the acetylide is lithiumphenyl acetylide.

7. A process according to claim 5 in which the acetylide is lithiummethyl acetylide.

8. A process according to claim 5 in which the dithiophosphonothioate is0,0,0,O'-tetraethyl dithiophosphonothioate.

9. An insecticidal composition comprising a major amount of inertcarrier and a minor but eiiective amount of a phosphorodithioaterepresented by the general formula:

ll RCEC-S-P (O Rm wherein R is a radical selected from the groupconsisting of lower alkyl, phenyl and naphthyl and R is a lower alkylradical.

10. An insecticidal composition according to claim 9 in which thephosphorodithioate is 0,0-diethyl, S-phenylethynyl phosphorodithioate.

11. An insecticidal composition according to claim 9 in which thephoshorodithioate is 0,0-dimethyl, S-phenylethynyl phosphorodithioate.

12. An insecticidal composition according to claim 9 in which thephosphorodithioate is 0,0-diethyl, S-methylethynyl phosphorodithioate.

References Cited in the file of this patent UNITED STATES PATENTS2,865,801 Baker et al Dec. 23, 1958 2,906,661 Baker et a1. Sept. 29,1959 FOREIGN PATENTS 1,063,148 Germany Aug, 13, 1949 UNITED STATESPATENT OFFI-[CE CERTIFICATE, OF CORRECTION Patent No. 3,019,159 January30, 1962 Bernard Miller It is hereby certified that error appears in theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

' Column 1, line 11, for "'reprented" read represented same column 1,line 35, for "alkli" read alkali column 2, line 12, for "precipiated"read precipitated -r; column 3, line 35, strike out "and aryl" andinsert instead phenyl and naphthyl-=g column 4, line 22, for"phosghorodithioate" read phosphorodithioate Signed and sealed this 19thday of June 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Atteflting Officer Commissioner of Patents

1. A PHOSPHORODITHIOATE COMPOUND REPRESENTED BY THE GENERAL FORMULA: